Life is rhythmic. Astronomical forces, such as the rotation of our planet, generate persistently rhythmic environmental cycles on earth that have favored the selection of endogenous biological clocks. These clocks have been described in all major taxa from cyanobacteria to plants and animals. For example, the Earth's rotation leads to cyclic changes in environmental factors such as light or temperature. This has favoured the evolution of the well-known circadian clock. Without any environmental signal, the clock runs in about (circa-) 24h, while under entrainment by environmental time-givers, it is synchronised to the 24h-solar day. Biological rhythms are not restricted to single days. Tidal rhythms occur with marine tides that cycle in 12.4h, Lunar rhythms occur with the moon’s phases in 29.5 days, and annual rhythms comprise the seasonal cycles, reoccurring every 365 days. Biological rhythms are generated and maintained molecularly and can be found at the molecular, biochemical, cellular, organ, and behavioral levels.
The dysregulation of biological rhythms is often closely associated with metabolic, reproductive, and immune disorders. Intensive research on biological rhythms currently focuses on standard model organisms, including mice, zebrafish, and fruit flies. However, biological rhythms show considerable mechanistic differences among species, and research on non-model systems is greatly needed to understand the diversity of these mechanisms and their influences on an organism’s biology, growth and development. Currently, research relating to the biological rhythms of marine organisms is relatively lacking. Given the drastic changes predicted for the marine environment due to climate change, there is an urgent need to characterize the interactions of marine biological clocks and their natural environment cues.
In order to understand how organisms’ biological rhythms vary under current and predicted environmental conditions, the proposed work aims to characterize the effects of variations in dominant environmental zeitgebers (especially light and temperature) on the biological clocks and behaviors of marine organisms. Obtaining these data from organisms in natural environments or industrialized culture conditions will enable the development of specific technical guidelines for aquaculture practices. More broadly, by characterizing the natural and changing forcings that govern the dynamics of marine ecosystems, we will also understand the range of regulation and the plasticity of the temporal structure of marine organisms and thus their capacity to adapt to changes caused by anthropogenic factors.
Specific themes include:
• Effects of light (i.e., light intensity, photoperiod, and spectral composition) or temperature on rhythmic behaviors (i.e. movement, feeding, and courting) of aquatic organisms;
• Effects of predation stress, interspecific competition, starvation, and feeding pattern on rhythmic behaviors;
• Plasticity of aquatic organisms’ behaviors and biological rhythms (timescales ranging from the tides to seasons) considering climate changes scenarios (temperature, acidification, hypoxia);
• Effects of cyclic changes of intestinal microbial communities on the feeding rhythm of aquatic organisms;
• Effects of light or temperature on the onset time of biological rhythms;
• Responses and adaptation mechanisms of nocturnal marine organisms to light at night;
• Effects of light and temperature on the early-stage embryonic development of aquatic organisms and the cyclic maturation of gonads.
Life is rhythmic. Astronomical forces, such as the rotation of our planet, generate persistently rhythmic environmental cycles on earth that have favored the selection of endogenous biological clocks. These clocks have been described in all major taxa from cyanobacteria to plants and animals. For example, the Earth's rotation leads to cyclic changes in environmental factors such as light or temperature. This has favoured the evolution of the well-known circadian clock. Without any environmental signal, the clock runs in about (circa-) 24h, while under entrainment by environmental time-givers, it is synchronised to the 24h-solar day. Biological rhythms are not restricted to single days. Tidal rhythms occur with marine tides that cycle in 12.4h, Lunar rhythms occur with the moon’s phases in 29.5 days, and annual rhythms comprise the seasonal cycles, reoccurring every 365 days. Biological rhythms are generated and maintained molecularly and can be found at the molecular, biochemical, cellular, organ, and behavioral levels.
The dysregulation of biological rhythms is often closely associated with metabolic, reproductive, and immune disorders. Intensive research on biological rhythms currently focuses on standard model organisms, including mice, zebrafish, and fruit flies. However, biological rhythms show considerable mechanistic differences among species, and research on non-model systems is greatly needed to understand the diversity of these mechanisms and their influences on an organism’s biology, growth and development. Currently, research relating to the biological rhythms of marine organisms is relatively lacking. Given the drastic changes predicted for the marine environment due to climate change, there is an urgent need to characterize the interactions of marine biological clocks and their natural environment cues.
In order to understand how organisms’ biological rhythms vary under current and predicted environmental conditions, the proposed work aims to characterize the effects of variations in dominant environmental zeitgebers (especially light and temperature) on the biological clocks and behaviors of marine organisms. Obtaining these data from organisms in natural environments or industrialized culture conditions will enable the development of specific technical guidelines for aquaculture practices. More broadly, by characterizing the natural and changing forcings that govern the dynamics of marine ecosystems, we will also understand the range of regulation and the plasticity of the temporal structure of marine organisms and thus their capacity to adapt to changes caused by anthropogenic factors.
Specific themes include:
• Effects of light (i.e., light intensity, photoperiod, and spectral composition) or temperature on rhythmic behaviors (i.e. movement, feeding, and courting) of aquatic organisms;
• Effects of predation stress, interspecific competition, starvation, and feeding pattern on rhythmic behaviors;
• Plasticity of aquatic organisms’ behaviors and biological rhythms (timescales ranging from the tides to seasons) considering climate changes scenarios (temperature, acidification, hypoxia);
• Effects of cyclic changes of intestinal microbial communities on the feeding rhythm of aquatic organisms;
• Effects of light or temperature on the onset time of biological rhythms;
• Responses and adaptation mechanisms of nocturnal marine organisms to light at night;
• Effects of light and temperature on the early-stage embryonic development of aquatic organisms and the cyclic maturation of gonads.